Various multi-component fibers are known. Examples include fibers that have a low temperature melting or softening sheath covering a higher melting core. Multi-component structures may be useful, for example, for fiber bonding, wherein the sheath, for example, when melted or softened serves as a bonding agent for the core.
In the oil and gas industry, production of oil and/or gas is sometimes increased using hydraulic fracturing, which involves injecting a viscous fracturing fluid or a foam at high pressure into a subterranean well to form fractures. As the fracture is formed, a slurry of a particulate material, referred to as a “propping agent” or “proppant”, in the fluid or foam is carried into the fracture. Upon release of the pressure, the proppants form a pack which serves to hold open the fractures, thus providing a highly conductive channel in the formation.
The efficacy of the hydraulic fracturing-fracture propping approach may be hindered by undesired transport of the proppant during clean-up operations or during production from the well. The transport of proppants, which is also known as flow-back, may restrict flow in the well bore, increase fluid friction, and contaminate produced fluids and therefore is undesirable.
Several different approaches have been used to address the problem of flow-back. Some fibers have been used in combination with proppants for flow-back control, and the modification of proppant geometry including the aspect ratio and particle size distribution has been investigated. Resin coated proppants have also been used. Resin coated proppants are expected to adhere to each other downhole to form an integrated proppant block. Different types of resin coatings have been used, including thermosetting resins (e.g., an epoxy or phenolic) and thermoplastic elastomers (e.g., acrylic resins). A disadvantage of resin coated proppants for proppant flow-back control is the potential premature curing of the proppant, and their required compatibility with the components of hydraulic fracture fluid (e.g., breakers) provides challenges.
Despite the advances in the technologies for flow-back control, there is a need for additional flow-back control options.